module Exercise_7 where
import Data.List
import Data.Function
import Data.Ord

{-WETT-}
trancl :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))]
trancl r = if r == new
           then r
           else trancl new
  where
    new = nubBy ((==) `on` snd)
          $ sortBy (comparing fst)
          $ r ++ [(c1+c2, (a, d)) | (c1, (a, b)) <- r, (c2, (c, d)) <- r, b == c]
{-TTEW-}